1. Field of the Invention
The present invention relates to a wobble plate type refrigerant compressor, and more particularly, to a lubricating mechanism provided at a ball-and-socket joint between a wobble plate and a piston rod in the wobble plate type refrigerant compressor.
2. Description of the Prior Art
A wobble plate type refrigerant compressor having a lubricating mechanism provided at a ball-and-socket joint between a wobble plate and a piston rod is disclosed in Japanese Utility Model Application Publication No. 52-169106.
Referring to FIG. 1, the wobble plate type refrigerant compressor includes cam rotor 300 which is fixed on a drive shaft (not shown) by any suitable means so that cam rotor 300 is rotated along with the drive shaft. Cam rotor 300 includes annular projection 300a projecting form inclined surface 300b thereof. Wobble plate 310, made of an aluminum alloy, is mounted on annular projection 300a of cam rotor 300 through bearing element 320 and is disposed on inclined surface 300b of cam rotor 300 through thrust needlebearing 330. Bearing element 320 includes flange portion 320a formed at one end thereof so as to prevent the axial movement of wobble plate 310. By means of bearing element 320 and thrust needle bearing 330, wobble plate 310 nutates, but does not rotate, during the rotation of cam rotor 300. A piston (not shown) is connected to wobble plate 310 through piston rod 340 which is made of steel. Ball 341 at one end of rod 340 is firmly received in socket 311 of wobble plate 310 by caulking an edge of socket 311. However, ball 341 slides along an inner spherical surface of socket 311.
Since steel is harder than aluminum alloy, when ball 341 slides along the inner spherical surface of socket 311 during the operation of the compressor, abrasion at the inner spherical surface of socket 311 cannot be neglected. In order to resolve this defect, a small diameter axial hole 312, linking one end surface of wobble plate 310 facing inclined surface 300b of cam rotor 300 to the inner spherical surface of socket 311, is formed in wobble plate 310. Thus, small diameter axial hole 312 leads the suspended lubricating oil in a crankcase of the compressor to the inner spherical surface of socket 311.
However, since hole 312 is covered by thrust needle bearing 330, the suspended lubricating oil in the crankcase cannot be effectively led to the friction surface between the outer spherical surface of ball 341 and the inner spherical surface of socket 311. Therefore, the abrasion at the inner spherical surface of socket 311 cannot be sufficiently prevented.